Memory module
The following notes describe the types of dual inline memory modules (DIMMs) that
the server supports and other information that you must consider when installing
DIMMs:
v The server supports 333 MHz, 1.8V, 240 pin, PC2-3200 single-ranked double
data-rate (DDR) II, registered synchronous dynamic random-access memory
(SDRAM) with error correcting code (ECC) DIMMs. These DIMMs must be
compatible with the latest PC2-3200 SDRAM Registered DIMM specifications.
For a list of the supported options for the server, see http://www.ibm.com/servers/
eserver/serverproven/compat/us/.
v The server supports up to four memory cards. Each memory card holds up to
four DIMMs.
v There must be at least one memory card with one pair of DIMMs installed for the
server to operate.
v When you install additional DIMMs on a memory card, be sure to install them in
pairs. All the DIMM pairs on each memory card must be the same size, and type.

v You do not have to save new configuration information to the BIOS when

installing or removing DIMMs. The only exception is if you replace a DIMM that
was marked as Disabled in the Memory Settings menu. In this case, you must
re-enable the row in the Configuration/Setup Utility program or reload the default
memory settings.
v When you restart the server after adding or removing a DIMM, the server
displays a message that the memory configuration has changed.
v Install the DIMMs on each memory card in the order shown in the following
tables, depending on which memory configuration you want to use. You must
install at least one pair of DIMMs on each memory card.
Table 3. Primary memory card installation sequence
Memory card order Memory card DIMM pair
First 1 1 and 3
Second 2 1 and 3
Third 3 1 and 3
Fourth 4 1 and 3
Fifth 1 2 and 4
Sixth 2 2 and 4
Seventh 3 2 and 4
Eighth 4 2 and 4
Table 4. Alternate memory card installation sequence
Memory card order Memory card DIMM pair
First 1 1 and 3
2 and 4
Second 3 1 and 3
2 and 4
Third 2 1 and 3
2 and 4
32 IBM System x3950 Type 8878 and System x3950 E Type 8879: User’s Guide